Elisha gray



nmsnn GRAY, on druoneo, InnruoIs.

uwPRoveMEN-T lNrSPEAKING-ninnaP'Hie Nes.

Specification forIningE-'partof Letters Batent'No.

204,029, dated May 21, 187s; application niea March 21,1878;v

sundry applications for Letters Patent ofthe United Statesy are now-pending. v

The object/of my. invention is, while preserving the portable feature of the instrument, so as to enable it to be handled'with facility, to secure an increased volume and clearness of sound. y

These ends I attain by mounting two diaphragms, each providedwithian'- electro-magnet secured to the poles of the permanent U- shaped magnet, common to both, at such an angle with reference to each other as to admit of the use of acommon mouth-piece so shaped as to allow the lips of the speaker to approximate as closely as possible to both diaphragms.

The subject-matter and advantages of my invention are hereinafter specifically designated'. Y

The accompanying drawings represent all my improvements as embodied in one apparatus in the best way now known to me. Obviously, however, some of these improvements may be used without the others, and in apparatus differing in details of construction from the one herein represented.

Figure 1 represents a plan or top view of my improved apparatus; Fig. 2, a view in elevation thereof, one side being shown in vertical section through the center of the magnet; and Fig. 3 shows an arrangement on circuit.

A battery may be employed arranged upon circuit, either as shown in my application led October 29, 1877, (Gase 3,) or as in that filed January 17, 1878. y

A permanent U-shaped or horseshoe steel magnet, A, constitutes the handle of the instrument, and may be highly iinished and ornamented, if desired. A rubber disk, B B', of about one-half an inch in thickness and of a diameter slightly larger than the diaphragm, is securedto each pole of the magnet by screws a. A small helix, C, wound upon ahard-rub- 4ber,` spool about an inch` in diameter, and

aboutf equal-'in4 length to the thickness of the disk B1B', is firmly inserted in each disk, and

provided with the ordinary connecting-wires.

softf-ironcore, D, screws into each pole of `ithepermanentmagnet A, and sis firmly secured therein by a check-nut, d.' The soft-iron core slides loosely through the helix, andris held Qpermanently charged by the pole of its respect jive magnet. This core is adjustable relatively to the diaphragm. by unscrewing the checknut andturning thecore back or forth with a screw-driver. untiliproperly adj usted, when the check-nut is screwed up again, thus holding fthe core` securely in position.

1 A diaphragm, E, is,i`1rmly secured'in place lbetween. the disk B and the screw-cap F. Rings c, of paper or other suitable material,

are interposed between the diaphragm and disk vand cap, respectively, and these parts are all securely clamped together by a brass ring, G, provided with a flan ge, g, overlapping the disk and an internal screwthread, in which the cap F screws.

I do not claim in this application the use of rings of paper or other suitable material on either or both sides of the diaphragm, to act as a dampener or excluder of external vibrations, as such a ring is shown in another application for Letters Patent of the United States, led by me January 16, 1878.

I disclaim the combination of the disk, the

cap, the interposed diaphragm, and theflanged ring overlapping the disk and screwing over the cap to clamp the diaphragm firmly at its edges. I also disclaim two or more magnetic cores, whose enveloping helices or coils are placed in a circuit of one and the same line-wire, two or more vibrating diaphragms, and a single mouth-piece or vocalizing-chamber, when combined, arranged, and operated substantially as specified in the pending application of George M. Phelps, iiled February 11, 1878.

The mouth-piece H, of metal or other suit able material, terminates in a bifurcated tube, each branch being secured to its respective cap F by screws f, so as to bring the mouth of each tube over the center of its respectivev diaphragm.

The diaphragms, it will be observed, are arranged at an angle of about forty degrees with reference to each other, by which `means the lips of the speaker are brought very near both diaphragms, so that practically each diaphragm is actuated with the same energy as a single one constructed in the ordinary way, by which means I am enabled to generate almost double the electro-motive force that a single diaphragm will. In consequence of this organization articulate words are transmitted with greater force and clearness than they are with a single diaphragm under the same circumstances. t

Each telephone is a counterpart of the other. and the apparatus thus constitutes what I term a bipolar telephone.77 l

The handle, it will be observed, is loopshaped, affording a rm grasp to the operator, constituting a means by which it may be suspended or attached in any position desired, and serving as a common support for the telephones, by which they may be brought close together relatively to a common mouth-piece, the advantages of which construction are obvious.

What I claim as of my own invention, and desire to secure by Letters Patent, is

l. Abipolar telephone constructed, substantially as hereinbefore set forth, with two diaphragms approximatingeach other at one edge, arranged at an acute angle, and having a common mouth-piece, whereby the lips may be brought close to each diaphragm to increase the electro-motive force.

42. The combination, substantially as hereinbefore set forth, of two telephones mounted upon a common support at an acute angle to each other; with an interposed bifurcated mouth-piece secured to said support.

3. The combination, substantially as hereinbefore set forth, of a permanent magnet, two diaphragms mounted thereon at an acute angle v to each other, and approximating at one edge,

with an interposed bifurcated mouth-piece,

core may be adjusted relatively to the da.

phragm. y

- 5. The combination', substantially as herein before set forth, of two telephones, with a looped handle upon which they are mounted, and a common mouth-piece.

- 6. The combination, substantially as here-` inbefore set forth, of a permanent horseshoe g magnet, constituting a looped handle, with a telephone mounted on each pole thereof, and

an' interposed mouth-piece.

In testimony whereof I have hereunto subscribed my name.

ELISHA GRAY.

Witnesses iA. G. SwARTwoUT, G. M. MAYNADIER. 

